Maple Mustard Ham Rolls With Mac And Cheese

2 cup dried elbow macaroni (8 ounces) 2 tablespoon butter ½ cup chopped onion (1 medium) 2 tablespoon all-purpose flour ⅛ teaspoon ground black pepper 1 ¾ cup milk 1 ½ cup shredded cheddar cheese (6 ounces) 6 ounce American cheese slices (about 8 slices), torn Ground black pepper (optional)